Question 1196056
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Walt made an extra $10,000 last year from a part-time job. 
He invested part of the money at 4% and the rest at 3%. 
He made a total of $370 in interest. How much was invested at 3%?
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<pre>
Let x be the amount (in dollars) invested at 3%.

Then the amount invested at 4% is (10,000-x) dollars (the rest).


Having it, write the money equation for the combined interest

    0.03x + 0.04*(10000-x) = 370  dollars.


Simplify and find x

    0.03x + 400 - 0.04x = 370

    0.03x - 0.04x = 370 - 400

       -0.01x     =    -30

            x     = {{{(-30)/(-0.01)}}} = 3000.


<U>ANSWER</U>.  $3000 was invested at 3%.
</pre>

Solved.


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It is a standard and typical problem on investments.


If you need more details,  &nbsp;or if you want to see other similar problems solved by different methods, &nbsp;look into the lesson 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/coordinate/lessons/Using-systems-of-equations-to-solve-problems-on-investment.lesson>Using systems of equations to solve problems on investment</A>

in this site.


You will find there different approaches &nbsp;(using one equation or a system of two equations in two unknowns), &nbsp;as well as 
different methods of solution to the equations &nbsp;(Substitution, &nbsp;Elimination).


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lesson is the part of this online textbook under the topic &nbsp;"<U>Systems of two linear equations in two unknowns</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.